RAVENNA Networking Guide
V1.0/3
9
Selecting Components
Switches
Switches
In order to create a RAVENNA network you will need a Layer 2 switch, or switches, that meet the following
requirements:
1. Transmission Speed = Gigbit Ethernet
A Gigabit Ethernet switch operating at 1000 Mbit/s is recommended, as opposed to Fast (100 Mbit/s) or Standard
(10 Mbit/s) Ethernet.
2. Synchronization = PTP-Aware
In
mc
2
/Nova73
systems, synchronisation of the RAVENNA streaming network requires a PTP master clock
source. In the current release, this takes the form of a specially configured DALLIS sync frame which converts
incoming Wordclock, from the master sync reference, to PTP.
In other Lawo systems, you should consider installing a PTP Grandmaster. Currently, Lawo recommends using
Meinberg clock generators.
As a result, you will require a PTP-aware switch with this feature enabled.
In smaller RAVENNA streaming networks using crystal, sapphire or JADE, it is possible for nodes to
sync to an incoming stream. In this instance, a PTP Grandmaster is not required, and non-PTP
switches may be implemented. Please see "RAVENNA for crystal" or "RAVENNA for sapphire/
Nova17" for more details.
3. Capacity (Non-blocking) = dependent on number of RAVENNA nodes & bandwidth requirements
The capacity of the switch will depend on the number of RAVENNA nodes and their bandwidth requirements. It is
best to choose a non-blocking switch, where all ports are capable of simultaneous Gigbit transfer. This can be
determined by the switch capacity and number of ports - for example, if a switch has 10 ports, then its capacity
should be at least 20 Gbps (Gigabits per second), to cater for 1Gb Input and Output transmissions per port.
If long distance connections are required, then you should choose a switch that supports fibre optic
modules.
4. Energy Efficient Ethernet (EEE) or Power Saving = OFF
It is important that any EEE, Green Ethernet or power saving features can be disabled, as these can interfere with
RAVENNA's clock signals and real-time buffering.
5. Addressing = Multicast, with IGMPv2
The switch must support
multicast
addressing. This means that packets sent from a single device can be
received by multiple nodes at the same time (i.e. one to many). This differs from a unicast data network where
data packets are addressed to a single receiving node (i.e. one to one).
The switch should also support
IGMPv2 Snooping
with an active
Querier
and
Fast
or
Immediate leave
. IGMP
Querying/Snooping is a technique used by network switches to control the forwarding of Multicast data packets.
A switch with IGMP Querying/Snooping will forward Multicast data packets only to the ports that are members of
the Multicast group. Whereas, a switch without IGMP Querying/Snooping will broadcast Multicast data to all of its
output ports. As a result, the volume of Multicast traffic will be significantly reduced if a network switch supports
IGMP Querying/Snooping.
